Explosive release means with mechanical and electrical actuating means



Apnl30, 1963 N. J. BUTTERFIELD EXPLOSIVE RELEASE MEANS WITH MECHANICAL AND ELECTRICAL ACTUATING MEANS Filed April 4, 1960 INVEN TOR. NEIL. J. BUTTERFIELD A T TORNEVS United States atet 3&81359 Patented Apr. 30, 1963 EXPLOSIVE RELEASE MEANS WITH MECHAN- ICAL AND ELECTRICAL ACTUATING MEANS Neii J. Entterfield, Hartford, llL, assignor to 01in Mathieson Chemical Corporation, East Alton, Ili., a corporation of Virginia Filed Apr. 4, 1960, Ser. No. 19,666 1 Claim. ((11. 851) This invention relates to explosively actuated release means and more particularly to explosive bolts or links for detachably connecting one article to another.

Various types of explosively actuated release mechanisms or explosive bolts have been devised for jettisoning bombs, canopies and other stores from vehicles in flight. Such explosive bolts normally take the form of a hollowed cylinder containing an explosive charge. The majority of such devices rely upon the electrical ignition or initiation of the explosive charge which then detonates or forms disruptive gas pressure to sever the connection. This eype of electrically actuated explosive bolt has, in most instances, been found to be very reliable and serviceable. However, they are completely inoperative and of no use whatsoever in the event of a power failure. This shortcoming of electrically initiated explosive bolts is well recognized and attempts have been previously made to provide such devices that are operable by pneumatic pressure. These pneumatically operated release mechanisms are generally of the type in which retaining bolts or pins are propelled out of position by an explosive charge. In such devices, the pressure required to move the retaining pin is roughly proportional to the amount of weight it is supporting. Thus, when stores of appreciable weight are to be jettisoned, the amount of propellent and the gas pressure required to dislodge them is inordinately great and exceedingly hazardous.

It is, therefore, an object of the present invention to provide a new and novel explosive bolt or link overcoming the disadvantages of the prior art. A further object of the present invention is to provide an improved explosive bolt that can be actuated by non-electrical means. A more specific object of the present invention is to provide an explosive bolt that can be easily and reliably operated by fluid pressure.

In accordance with this invention, these and other objects are accomplished, generally speaking, by providing an explosive bolt body containing an explosive charge, a percussion or stab initiated primer, a firing pin and a pneumatic trigger. More specifically, this invention contemplates an explosive bolt having a hollow body containing an explosive charge intermediate its ends and having that portion of the body adjacent the explosive charge weaker than the remaining portions of the body. At least a portion of the body about the explosive charge can be rendered relatively weak by the provision of notches, grooves, appropriate thinning and the like, by heat treatment, or by other equivalent means. The explosive charge, which may be either of the propellent or brisant type, has an impact responsive initiating means in association therewith. When a propellent charge is used, the impact responsive initiator is generally a per cussion primer of the type normally used in ammunition. However, when a brisant explosive, such as cyclonite or the like is employed, the impact responsive initiating means can be a stab initiated detonator. One end of the hollow bolt body is fitted With a bored plug which accommodates the firing pin and the pneumatic trigger. The firing pin is preferably positioned in contact with the impact responsive initiating means but can be spaced therefrom in any conventional manner if so desired. The pneumatic trigger preferably takes the form of a striker rod contained in a counterbore of the plug and positioned 2 from the extremity of the firing pin by a shear pin, wire or other appropriate retaining means.

The main body of the firing pin is normally right cylindrical and is provided with a basal projection to contact the impact responsive initiating means, while the opposite end of the firing pin is tapered or curved to provide a generally conical configuration terminating in a central rod-like extension. The main body of the firing pin is contained in a counterbore of the plug opposite the pneumatic trigger or striker rod and the rod-like extension on the firing pin extends through a bore of the plug connecting the counterbores at its extremities. The tapered or conical portion of the firing pin is of the same general configuration as the surrounding counterbore. Thus, upon initiation of the explosive charge, the firing pin is forced back upon a mating surface to provide a gas-tight seal whose efiectivenes increases with the pressure generated. The metal-to-metal seal can be restricted to the area about the apex of the conical portion of the firing pin, or the entire conical area of the pin can serve as a sealing surface.

Although the present invention is primarily concerned with explosive bolts and the like which can be operated by fluid pressure, such devices which can be initiated either by electrical or fluid energy are also contemplated. Most conveniently, the electrical and impact initiating means are repositioned remote from one another. Simplicity of design normally dictates that the actuators be located at opposite ends of the explosive charge. However, in some instances, both of the initiating means can be positioned in close proximity.

The present invention and the manner in which it accomplishes its objects will be more readily understood by reference to the following specific example thereof taken in connection with the drawing illustrating a longitudinal cross-sectional view of a preferred embodiment.

The hollow body of the bolt indicated generally at 1 is provided with hexagonal portions as indicated at 2 and 3' to facilitate manipulation of the bolt. Connecting means such as screw threads 3a may be provided at each end of the bolt to facilitate connecting the bolt between elements which are to be separated one from the other when the bolt is fired. A peripheral groove 4 and internal notch 5 circle the central portion of the bolt about a propellant powder charge 6. Plug 7 is threadedly attached within the hollow body 1 and is provided with a pair of oppositely disposed counterbores. The counterbore closest to the propellent charge accommodates primer 8, primer retainer 9 and firing pin 10. The firing pin is provided with a centrally positioned basal protrusion 11 which is normally in contact or alignment with the primer. The rearward portion 12 of the firing pin is conically shaped and forms a mating fit with the tapered walls of the counterbore. Rod-like extension 13 on the firing pin passes through the bore connecting the two counterbores and extends into counterbore 14 which accommodates pneumatic trigger or striker rod 15. The striker rod is maintained in position by retaining pin 16 which passes through it and the adjacent wall of plug 7. Retaining pin 16 can be replaced by a wire or other similar means. Gas check 17 closes counterbore 14 and prevents passage of gas between the pneumatic trigger and the plug. As shown in the drawing, the gas check is in the form of a cup wad. However, a resilient O-ring positioned between the striker rod 15 and plug 7, or other conventional means can be used as a gas check.

The explosive bolt of this preferred embodiment is also provided with electrical initiating means carried by plug 18 which is screw threadedly aflixed in body 1. A pair of electrodes 19 are positioned in nylon or other insulating tubing 26 and pass through bores in plug 18. The interior ends of electrodes 19' are provided with nylon washers 21 and are connected by one or more bridge wires 22. The bridge Wires are embedded in ignition mix 23 which is in contact with base charge 6.

When the device is to be operated pneumatically, a tubing connected to a source of high pressure gas is attached to that end of the body approximate gas check 17 with the end of the retaining pin 16 unobstructed. Preferably, the source of high pressure gas is a conventional gas generating cartridge. However, any other source of compressed gas can be utilized with equal success. The striker rod 15' remains stationary until the gas pressure behind it reaches a level of about 500 p.s.i. At that point, retaining pin 16 is broken and striker rod 15 is driven with considerable force into contact with rod-like.

extension 13 of the firing pin. This results in basal protuberance 11 of the firing pin impinging upon the primer 8 with equal force. Primer 8 is thus initiated and the flame from the primer passing through flash hole 24 results in the ignition of powder charge 6. As the powder charge burns, the pressure within the bolt increases progressively and results in the rupture of the bolt around peripheral groove 4 and internal notch 5.

The pressure generated by the burning propellent charge 6 is much greater than that employed to drive the striker rod into contact with the firing pin. Thus, the firing pin is forced away from the propellent charge and into sealing relationship with the counterbore of plug 7. The seal between the firing pin and the corresponding counterbore is exceedingly effective and is capable of resisting pressures of the order of 150,000 p.s.i. After the explosive bolt has fired, the pressure on the base of the firing pin is released and the residual pressure in the bolt assembly is liberated upon ejection of the firing pm. When the retaining pin 16 is severed, the entire body of striker rod 15 and gas check 17 travel through counterbore 14 to a position beyond the hole in the plug and retaining pin 16. Thus, any residual pressure in the gas line is vented through this hole.

The present explosive bolt can also be operated electrically in the conventional manner. When an electrical discharge is desired, electrodes 19 are connected to a source of electrical power and a current is passed through them and through bridge wire 22. This results in ignition of charge 23 and the generation of a disruptive gas pressure by propellent charge 6 which results in the breakage of the bolt as described above. Whether the charge is fired electrically or pneumatically, the firing pin functions to form a seal preventing passage of gas around it.

The explosive bolt as described above has been found to be satisfactory and completely reliable and has been designed to pass very rugged environmental tests, including a 40 foot drop test, a 15 G shock test, and acoustic noise test.

The device described in the preferred embodiment was made of steel, but any other structural material such as ferrous alloys, aluminum, titanium, magnesium, and other non-ferrous materials, their alloys, and the like can also be utilized. In addition, any suitable thermo-responsive gas generating charge or brisant explosive charge can be used in lieu of the propellent powder charge.

Although the foregoing embodiment has been described in detail, many variations or modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

An explosive bolt comprising an elongate frangible body having connecting means at either end, an axial bore extending through the body, an explosive charge positioned within the bore intermediate the ends of the body, said body being grooved to provide a relatively weak area in the body external to the explosive charge, a percussion primer within the bore adjacent to one side of the explosive charge and an electrically actuated igniter adjacent the opposite side of the explosive charge, a plug rigidly afiixed within the bore and extending substantially from the explosive charge to one end of the body, the plug having first and second counterbores at either end and an intermediate connecting bore, the base of the first counterbore facing tthe explosive charge being tapered, a firing pin in said first counterbore having a basal protuberance normally in contact with said primer, the portion of the firing pin remote from the protuberance being tapered to form a mating fit with at least a portion of the counterbore, a rod like extension extending from said tapered portion through said intermediate connecting bore and terminating Within the second counterbore, a pressure responsive striker rod retained within said second counterbore and positioned from the end of the rod-like extension of the firing pin, rupturable pin means extending transversely through said plug and into said striker rod to retain said striker rod in said spaced condition, said striker rod being actuated by gas pressure emanating from a source of gas pressure, said pressure being of sufiicient force to rupture said pin means and drive said'striker rod into impacting engagement with said firing pin and thereby actuate said primer.

References Cited in the file of this patent UNITED STATES PATENTS 1,400,401 Allan Dec. 13, 1921 1,627,185 Krammer May 3, 1927 2,535,820 Temple Dec. 26, 1950 2,541,087 Musser Feb. 13, 1951 2,653,504 Smith Sept. 29, 1953 2,883,910 Nessler Apr. 28, 1959 2,949,822 Musser Aug. 23, 1960 

